Generally, a real-time clock (Real Time Clock, RTC for short) uses a 32.768 kilohertz (KHz) quartz crystal oscillator to provide a timing pulse. Because oscillation frequency output of the 32.768 KHz quartz crystal in the quartz crystal oscillator may have different frequency deviations in different temperatures, for an RTC, a frequency deviation means a time deviation, and the deviation is accumulated with passing of time. Therefore, when the RTC uses the 32.768 KHz quartz crystal oscillator to provide a timing pulse, the frequency deviation of the quartz crystal oscillator must be corrected according to a temperature, so as to achieve high-precision timing.
FIG. 1 is a schematic diagram of a general correction solution. Specifically, a correction solution for correcting frequency of the RTC is as follows: an external temperature sensor 100 collects a surface temperature of a quartz crystal in a quartz crystal oscillator 300 and sends the surface temperature to a micro controller unit (Micro Controller Unit, MCU for short) 200; the MCU 200 acquires a frequency deviation according to an input temperature value, and sends the frequency deviation as a frequency dividing coefficient to an integer frequency dividing circuit 400; the integer frequency dividing circuit 400 acquires a 1 Hz clock signal according to a signal provided by the quartz crystal oscillator 300 and the frequency dividing coefficient acquired from the MCU 200, and sends the clock signal to an RTC 500 for timing.
A major problem in the foregoing correction solution, however, is that, when a chip is powered off and is incapable of supplying power to the external temperature sensor, temperatures fail to be collected. In addition, the operation of the frequency coefficient requires the MCU, which wastes MCU resources.